Brake Lining; Replacement - Komatsu 830E-AC Shop Manual

7. Inspect piston cavities for damage similar to
Step 6 above, with particular attention to the
edge of the seal grooves. These must feel
smooth and sharp with no nicks or sharp projec-
tion that can damage seals or scratch pistons.
Seal groove surfaces must be smooth and free
of pits or scratches. Finish of cylinder wall is not
as critical as surface finish of piston. Surface
deterioration near entrance of cavity should be
hand polished very carefully to avoid enlarging
cavity beyond a maximum of 92.176 mm
(3.629 in.) inside diameter at the outer edge of
the seal groove. Power polishing or honing may
be used in cases of extreme surface finish dete-
rioration of cavity walls.
NOTE: Care must be taken that a minimum amount
of material is removed, within the previous maximum
diameter limitation of 92.176 mm (3.629 in.). Power
polishing will not normally be required, and should
not be used as a standard overhaul procedure.
8. Inspect inlet and bleeder ports in housings for
damage to threads or seal counter bores.
Thread damage that cannot be repaired by use
of a 0.475-20 UNF-2B tap will require housing
to be replaced.
9. Inspect retainer plates (7 & 8) for bent or
cracked condition, replace if such damage is
found. Inspect retainer plate bolts (6), and
tapped holes in housing.
NOTE: These bolts are highly stressed and should
be replaced whenever their condition appears
questionable. A 3/4-16 UNF-28 tap lubricated with a
light oil may be used to inspect tapped holes in
housings for thread damage and to clean up any
minor thread roughness.
10. Brake housings and pistons should be thor-
oughly cleaned. After cleaning, passages, cavi-
ties, and external surfaces should be blown dry
with clean, dry, compressed air. Piston should
also be cleaned and blown dry.
NOTE: Cleaned and dried parts should not be left
exposed for any appreciable time without a
protective coating of lubricant; for short term storage,
coating all internal cavities, passages, and bosses
with hydraulic fluid will be adequate protection; for
longer term storage wipe cavities, connector bosses,
and threads with a protective grease, such as
petroleum jelly.
J05024 10/06

BRAKE LINING

Replacement

Each front wheel speed disc assembly has three
(some trucks may have four) calipers on one disc.
Each caliper has six pistons and two linings, three
apply pistons and one lining for each side of disc.
Lining should be changed when friction material is
worn to 3.22 mm (0.125 in.) thickness.
Failure to replace lining when worn to limits will
result in loss of braking and possible cata-
strophic failure.
Rockwell Wheel Speed Front Disc Brakes
1. To replace front linings, remove front tire and
rims, refer to "Wheel and Tire Installation", Sec-
tion "G".
2. Remove end plates (7 or 8) Figure 5-3 from
either end of caliper.
3. Pry between lining and disc to force pistons to
bottom in caliper housing.
4. Remove lining from inboard and outboard sides
of disc.
5. Inspect dust seals. Seals should be soft, pli-
able, and show no evidence of hardening or
rupture. If damage is observed, the dust covers
must be replaced. This will require disassembly
of the caliper.
6. Inspect end plates for wear. Replace if grooves
will not allow lining back plate to slide freely.
7. IMeasure the thickness of the disc. If 20 to 25%
of the disc wear surface is worn below 28.7
(1.13 in.), the disc must be replaced. Refer to
Figure 5-4.
J5-7